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A concave mirror, or converging mirror, has a reflecting surface that is recessed inward (away from the incident light). Concave mirrors reflect light inward to one focal point. They are used to focus light. Unlike convex mirrors, concave mirrors show different image types depending on the distance between the object and the mirror.
Mangin mirrors were used in searchlights, where they produced a nearly true parallel beam. Many Catadioptric telescopes use negative lenses with a reflective coating on the backside that are referred to as “Mangin mirrors”, although they are not single-element objectives like the original Mangin, and some even predate Mangin's invention.
There are statements about reflected light illumination using a concave mirror, such as: "The first arrangement of this kind was the Lieberkühn mirror from 1738." [ 18 ] In contrast, a book from 1988 states: "J.N. Lieberkühn introduced the concave mirror named after him for reflected light illumination in 1738, as it was used in similar form ...
Catoptrics is the title of two texts from ancient Greece: . The Pseudo-Euclidean Catoptrics.This book is attributed to Euclid, [3] although the contents are a mixture of work dating from Euclid's time together with work which dates to the Roman period. [4]
A mirror reflecting the image of a vase A first-surface mirror coated with aluminium and enhanced with dielectric coatings. The angle of the incident light (represented by both the light in the mirror and the shadow behind it) exactly matches the angle of reflection (the reflected light shining on the table). 4.5-metre (15 ft)-tall acoustic mirror near Kilnsea Grange, East Yorkshire, UK, from ...
This page was last edited on 17 May 2009, at 18:26 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply ...
The Gregorian telescope consists of two concave mirrors: the primary mirror (a concave paraboloid) collects the light and brings it to a focus before the secondary mirror (a concave ellipsoid), where it is reflected back through a hole in the centre of the primary, and thence out the bottom end of the instrument, where it can be viewed with the aid of the eyepiece.
For concave lenses, the focal point is on the back side of the lens, or the output side of the focal plane, and is negative in power. A lens with no optical power is called an optical window, having flat, parallel faces. The optical power directly relates to how large positive images will be magnified, and how small negative images will be ...